The throughput of the forward channel (or downlink) of a wireless network is significantly affected by the scheduling algorithm employed by the base stations of the wireless network. A large number of algorithms have been developed for scheduling the transmissions of voice and data traffic from base stations to subscriber stations (or mobile stations, mobile terminals, etc.). These scheduling algorithms generally allocate to each subscriber station a time slot, a frequency assignment, or a code (e.g., Walsh code), or a combination of these elements, for receiving traffic in the forward channel.
There are different types of scheduling algorithms for different types of wireless protocols. As a result, there are unique schedulers and scheduling algorithms for spatial division multiple access (SDMA) networks, time division multiple access (TDMA) networks, orthogonal frequency division multiplexing (OFDM) networks, orthogonal frequency division multiple access (OFDMA) networks, code division multiple access (CDMA) networks, and others.
New wireless standards, such as the proposed WiBro standard and the IEEE-802.16d/e standard, are being developed that will implement both OFDMA technique and SDMA techniques. Thus, a network base station will be able to transmit to subscriber stations (or mobile stations, mobile terminals, etc.) using multiple carriers (i.e., OFDMA) that are transmitted using beam-forming techniques (i.e., SDMA).
However, none of the known prior art schedulers and scheduling algorithms is specifically directed to a spatial division multiple access-enabled orthogonal frequency division multiple access (SDMA-OFDMA) downlink system.
Therefore, there is a need in the art for an improved scheduler for use in a spatial division multiple access (SDMA)-enabled orthogonal frequency division multiple access (OFDMA) wireless network.